Rectifier



May 2l, 1935. H. G. ANDRE RECTIFIER Original Filed Aug. 24, 1929 Panarea May 21, 193s 2,001,698

UNITED STATES PATENT ori-ICE l l la Henri G. Andre. Suresnes. France Application August 24, 1929, Serial No. 388.181. llleiczwsed August 22. 1934. In France October 13 Claims. (Cl. 175-368) 'I'his invention refers to an electrochemical contact be as intimate a contact as possible. rectiiierof current, with solid electrodes in con- When they are coated with their nal chemical tact, characterized by the automatic regeneration composition they are not very malleable, and a of the surfaces in contact. heavy pressure which would be permissible in the 5 It has been pointed out, as av matter of fact, case of one or two soft electrodes is invariably in- 5 that all the devices of this kind are very short jurious to the good preservation of the contact. lived, are unreliable in their operation, and are 'I'his invention also bears on the securing on destroyed even at rest, due to the decomposithe spot of the i'lnal chemical state of the election or the combination of the substances facing trodes in contact with a maximum of contact each other which react between themselves or points. l0 with the elements of the ambient air. Particularly in the case of silver sulfide, a

This is the case in particular of the rectifiers rather brittle product under certain conditions, provided with metal oxides and metal suldes, the the invention makes provision for the shrouding operation of which is satisfactory but momenof the cathode by means of a silver element 15 tarily. which upon its being sulfurated, allows through 15 Indeed, all these types are the seat of numerous its porosity, of the conveyance of the regenmicroscopic sparks which heating locally the parerating product. The anode will therefore be ticles of the substances in contact, bring about constituted preferably by a thin perforated plate in the presence of steam a reduction of the oxide or even'better, by a. silver wire wound around or of the suliide used and thereupon asubsequent the cathode. It will thereupon be transformed 20 bad rectication. superiicially into a suliide or subsulde through This decomposition may be made slower by the emersion in a melted sulfur bath and through drying of the ambient air or by the limitation of heating by a higher temperature. 'Ihis treatthe water vapor contents of the air as suggested ment shall be renewed a number of times which 5 hereinafter, but this necessary safeguard is inlwill bethe greater the thicker the coat of sul- 25 sumcient because the dampness absorbed by the furation sought to be obtained; the best thickproducts in contact may in turn exercise an inness will be determined by a compromise between jurious action. the inverse tension that is to be borne by the For the condition of the substances in contact rectiiier and the minimum Joule loss.

3o not to undergo any change, it is necessary to re- My invention will be best understood from the 30 sort to a chemical agent which under the inilufollowing description of an exempliflcation thereence of the sparks keeps the composition of the of, reference being had to the accompanying electrodes unchanged. drawing, in which For instance, if there is used as anode sulde Fig. l is a view of the rectifying element;

of copper or silver or of other electro-positive Fig. la is an enlarged cross-sectional view of 35 metal, as speciiled, for example, in the patent to a portion of the element shown in Fig. 1; Lilienfeld, No. 1,611,653, it will be necessary to Fig. 2 shows a diierent form of rectifying place close to the sulfide a product capable of element; resulfurizing in aproper manner, the contact sur- Fig. 3 illustrates an arrangement for leading 40 face. The use of sulfur would appear practicable the current into the rectifying element; 40

at tlrst glance, but its low melting point makes it Fig. 4 shows my rectifying element enclosed unsuitable because it would soon isolate the elecin a sealed envelope; trodes from each other. On the other hand, it is Figs. 5 and 6 show two arrangements for necessary that the insulating film of metal oxide mounting my rectifying element in the conon the cathode be kept up in a uniform and container; 45 tinuous manner. 'I'his invention makes use of Fig. '7 shows an arrangement for supplying a concentrated sulfuric acid which offers athorough reserve of regenerating liquid to my novel recsolution of the problem in all cases where sulildes tifying element; i l are resorted to. Fig. 8 illustrates an t for sealing In this invention instead of a sulphide I have the rectifying element within a container; and 50 discovered that a metal phosphide may be used Fig. 9 shows another arrangement for supportfor the anode in which case phosphoric acid is ing the assembly shown in Fig. 8 within an out-l used to accomplish the desired results specied er vented container. above, The cathode of my novel rectifying device pref- 1t is likewise eential that the products in erably consists of an'oxidizable metal, such as 55 sicon or an alloy thereof. Of course it will be understood that any of the other oxidizable metals which are commonly used in the type of rectifier with which I am dealing, may also be used as the cathode as described, for example, in the patent to Lilienfeld, No. 1,611,653, and the patent to Pawlowski, No. 830,924. For the anode I utilize either a metallic sulphide, such as silver, or copper sulphide or phosphide, such as silver or copper phosphide. The anode and cathode are placed in intimate contact with each other, the cathode in its operating condition having formed thereon a layer of its oxide. As pointed out above, my invention contemplates the use of a regenerating material for maintaining the surfaces of both the anode and the cathode. In the case where sulphides are used, this material consists of concentrated sulphuric acid which is placed in immediate vicinity of the contact between the cathode and anode. In the case of phosphides, this material consists of phosphoric acid.

Fig. 1 shows the rectifying element referred toabove by way of example. It shows cathode 2, on which is wound anode I consisting of a silver wire. The enlarged cross-section in Fig 1a shows sulfuration coat 3 forming after the sulfuration and the oxidation coat 4, brought about by the action of the regenerating sulfuric acid with which the coils have been impregnated after sulfuration.

In the special cases of sulfide of silver, cathode 2, (Fig. 2) may be coated, due to the porosity of this compound, with these melted substances, there being thereby secured the coating 3'. Thereupon the current may be led in either (Fig.

2) by a wound silver wire or (Fig. 3) by a metal powder 6, which has the advantage of keeping up a reserve of regenerating liquid. 'I'his powder would not exercise any so-called valvular effect either on the sulfide vof silver or on the metal Wall through which the current is brought in, and for this purpose it will itself consist of silver as the metal wall itself.

Fig. 3 shows the leading of the current into anode 3 of sulfide of silver through powder 8 which in turn receives this current from the inner wall of container 5.

As it has been pointed out at the outset, it is absolutely necessary to remove the rectifying element from contact with moist air. If the quantity of regenerating acid is small or if the product used` does not give rise to any release of gas. it will be advisable to enclose quickly the element irnmediately after its manufacture in a glass bulb where a vacuum will be produced. There may be adopted with advantage an arrangement similar to the one adopted in the case of incandescent electric lamps.

Fig. 4 shows such an arrangement; the rectifying element I-2 is set up on a glass foot 1 soldered to bulb 8 which may be closed without a previous formation of vacuum, or preferably with a previous formation of vacuum, it being still better to enclose an additional water absorbing medium having a greater absorption power than the acid or the regeneration used.

If the liquid used is partially electrolyzed and if the quantity utilized is large, there arises the risk of a dangerous increase of the pressure inside' of the bulb. The substitution of metal for glass would merely delay the danger of an explosion.

Resort has therefore been had to a mechanical valve device which is one of the essential features of the type of apparatus covered by this invention.

By measure of safeguard there is rst of all effected a plugging by means of a plastic substance set on the outlet of a metal tube containing the electrodes. To make easy such shutting the electrodes are set up at the bottom of the tube either according to the arrangement shown in Fig. 5, or according to the arrangement shown in Fig. 6. In these two assemblies the cathodes are provided with a shoulder which rests on the bottom of the tube through the insertion of insulating mica washers 9. The metal washer I holds the cathode against the bottom of the tube. The washers are coated in advance with bakelite varnish or other substances absolutely water proof.

Fig. 7 shows the mechanical layout of Fig. 5, with a reserve `I I of regenerating liquid shut up in a neutral substance such as silica or of spun glass.

'Ihe electrodes being thereby fastened to the bottom of metal tube 5, there is established an upper plugging which is isolated by capillarity from the liquid reserve through a glass tube I2 (Fig. 8) resting on mica washers I 3. Above the upper washer there is an asbestos stopper impregnated with bakelite varnish Il, 'which is almost tight. A coating of gas tar I or of any other plastic wax makes the sealing a thorough one.

This latter protection may prove suillcient if the release of gas is small; it insures the perfect keeping of the rectier while in storage and not in operation but if while the rectifier is in service plastic material I5 is pushed down, it may happen that it does not come back to seal the tube, and in such a case provision is to be made for a device affording the possibility of draining the released gas and barring the way of an inffux of water vapor.

This invention contemplates therefore in this connection an additional mechanical valve.

The arrangement of this mechanical valve is made dilcult by the circumstance that in view of the dangerof the gas inside exploding accidently, it is necessary to. avoid any compression of such gases and on the other hand, the sealing should be as good as possible to insure a proper keeping.

The inner pressure being intended to be small, the flap of the valve shall be made preferably of rubber or of any other similar substance.

The use of rubber bars, of course, does not allow the resort to any exaggerated high temperature. It is therefore necessary, upon the rectifier becoming somewhat heated, to isolate thermally the valve seal of the housing.

For this purpose the valve seal is made of a thermic insulating material such as cast bakelite.

. Fig. 9 shows by way of example the arrangev, ment of the complete elements of an electrochem- -ical rectifier with automatic regeneration and of remarkable keeping qualities.

It shows the use of the rectifying element of Fig. 6, sealed according to the arrangement of Fig. 8. The rectifier is set up in a socket I6 (Fig 9) Edison type, containing tar I1 which increases the seal while holding the apparatus; the connection of the latter is effected on the one hand with central contact Il, of the cap, and on the other hand with thev mass of a sheath I8.

This tube is inserted by a casting process in plug 20 made of bakelite or other similar moulded material. The plug itself is arranged in such a manner as to receive in the upper hole a rubber disk 2i which seals the narrow passage 22, leadingtothe insideofthehousing. Thediskis pressed against hole 22 by a spring 23 adjusted by screw 2l, held in a threading of the plug. Release canals which are not shown, may be driven radially in the plug between its outer surface and the housing of spring 23.

It is clear that the system of protection described above surmounted by its valve plug may contain any number of rectiers for objects of enonomy, the connections between the elements being made inside the housing supporting the valve, further means of connections (clamps, terminals, etc.) being furthermore contemplated to make sure the connection of the apparatus with outside circuits.

I claim:

l. A rectifier comprising a cathode of oxidizable metal, an anode of a sulphide of an electropositive metal in contact with said cathode, and concentrated sulphuric acid immediately adjacent the contacting surfaces of said cathode and anode.

2. A rectifier comprising a cathode having a layer of metallic oxide on its surface, an anode having a layer of a sulphide of an electro-positive metal on its surface, said cathode and anode surfaces being in contact with each other, and concentrated sulphuric acid supplied to said contacting surfaces.

3. A rectifier comprising a cathode of oxidizable metal, an anode in close proximity thereto, a sulphide of an electro-positive metal in contact with and connecting said cathode and anode, said sulphide being porous, and concentrated sulphuric acid provided through said sulphide.

4. The method of making a rectifier which comprises placing on the surface of an oxidizable metal, another electro-positive metal having a stronger ailinity for sulphur than said first metal. said second-named metal being in close contact with the surface of said first-named metal, converting the surface of said second-named metal into its sulphide, supplying a concentrated sulphuric acid to the contacting surfaces of said metals, a coating of oxide being formed on the surface of said first-named metal at any time during the above-mentioned steps.

5. A rectifier comprising a cathode of oxidizable metal, an anode of a sulphide of an electropositive metal in contact with said cathode, and a metallic powder in contact with said anode serving as a current lead thereto.

6. A rectifier comprising a cathode of oxidizable metal, an anode of a sulphide of an electropositive metal in contact with said cathode, concentrated sulphuric acid supplied to the contacting surfaces of said cathode and anode, said rectifier being disposed in a container, and means associated with said rectifier for venting the gases formed.

7. A rectifier comprising a cathode of oxidizable metal, an anode of a lsulphide of an electropositive metal in contact with said cathode, concentrated sulphuric acid supplied to the contacting surfaces of said cathode and anode, said rectifier being disposed in a container, and means associated with said rectifier for venting the gases formed, said venting means being thermally insulated from the rectifier itself.

8. A rectifier comprising a cathode of oxidizable metal, an anode of a sulphide of an electropositive metal in contact with said cathode, concentrated sulphuric acid supplied to the contacting surfaces of said cathode and anode, said rectifier being disposed in a container, and means associated with said rectifier for venting the gases formed, said venting means comprising a one-way valve allowing escape of gases from the interior of said container but preventing entrance of fluids into said container.

9. A rectifier comprising a cathode of an oxidizable metal, an anode of silver sulphide in contact with said cathode, and a concentrated sulphuric acid immediately adjacent the contacting surfaces of said cathode and anode.

10. A rectifier comprising a cathode of an oxidizable metal, an anode of copper sulphide in contact with said cathode, and a concentrated sulphuric acid immediately adjacent the contacting surfaces of said cathode and anode.

l1. A rectifier comprising a cathode having a metallic oxide on its surface, lan anode having a sulphide of an electro-positive metal on its surface, said cathode and anode surfaces being in contact with each other, and a re-sulphurizing and re-oxidizing medium supplied to said contacting surfaces.

12. A rectifier comprising a cathode having a metallic oxide on its surface, an anode having a sulphide of an electro-positive metal on its surface, said cathode and anode surfaces being in contact with each other," and a sulphur and oxygen containing-compound supplied to said contacting surfaces.

13. The method of making a rectifier which comprises placing on the surface of an oxidizable metal another electro-positive metal having a stronger afiinity for sulphur than said first metal,

said second-named metal being in close contact with the said first-named metal, converting the surface of said second-named metal into its sulphide, supplying a sulphurizing and oxidizing medium to the contacting surfaces of said metals, a coating of oxide being formed on the surface of said first-named metal at any time during the above-mentioned steps.

a HENRI G. ANDR. 

